I am adding to this as we have this issue. We have subscribers who have unsubscribed and are STILL on the list for newsletters, therefore being sent the newsletter. When they unsubscribe, the plugin does not automatically remove them from the lists they are on.
Our hosting provider has flagged the account because it is in violation of the CAN-SPAM act as well as a lot of other privacy guidelines.
Is there any chance that you all are going to add an update for this? If not, we will have to search for another newsletter plugin.